Optical modulator

About: Optical modulator is a research topic. Over the lifetime, 14068 publications have been published within this topic receiving 196932 citations.

Linearization of an interferometric modulator at microwave frequencies by polarization mixing

Abstract: The linearization of all interferometric modulator by polarization mixing over the suboctave frequency range of 3.6 to 5.6 GHz is reported. A traveling-wave modulator fabricated in X-cut LiNbO/sub 3/ utilizing the r/sub 33/ (TE) and r/sub 13/ (TM) electrooptic coefficients was employed. The effective V/sub pi /s (from a 50- Omega source) were 14 and 43 V for the TE and TM modes, respectively. The modulator response was not optimized for this frequency range. A DC voltage was used to separate bias electrodes to adjust the relative TE and TM phase bias. A polarizer was placed between the diode-pumped Nd:YAG laser source, and the modulator to adjust the relative TE and TM optical power. The modulator output was measured with a high-speed photodetector and spectrum analyzer. >

Interferometer with a single-mode waveguide coil

Abstract: An interferometer with a single-mode optical waveguide wound in a coil which waveguide has a surface at each end for the acceptance of the light into the waveguide ends and for the display of light in the waveguide characterized by an improvement comprising at least one optical directional coupler having four input/output ends being provided. One of the four input/output ends is coupled into one of the pair of ends of the waveguide forming the coil and a second of the input/output ends is coupled to the other end of the pair of ends of the waveguide forming the coil. Preferably, the coupling of light from a light source utilizes a second additional directional coupler, which has an input/output end coupled to a third input/output end of the first mentioned coupler and the device preferably has a pair of light sensitive elements with one of said elements receiving a superimposed image from the fourth input/output end of the first mentioned coupler and the other receiving light from one of the input/output ends of the second or additional coupler.

Compensation of the Dispersion-Induced Power Fading in an Analog Photonic Link Based on PM–IM Conversion in a Sagnac Loop

Abstract: An analog photonic link with the compensation of the dispersion-induced power fading is proposed and demonstrated based on phase modulation to intensity modulation conversion in a Sagnac loop. Due to the velocity mismatch of the modulator, only the incident light wave along the clockwise direction is effectively modulated by the radio frequency signals, while the counterclockwise light wave is not modulated. After combining the two light waves in a polarizer, an intensity modulated optical signal is generated, which can be directly detected. In addition, the phase difference between the two light waves can be adjusted through the polarization controller before the polarizer. This feature is used to shift the frequency response of a dispersive link to compensate the dispersion-induced power fading at any working frequency. Experimental results show that the power fading after transmission over both 25 and 50 km lengths of fiber in a conventional intensity modulated link can be successfully compensated in the proposed link, and thus, a high and constant link gain over a large frequency range is achieved. The spur-free dynamic ranges of the link before and after fiber transmission are also measured.

Optical modulator module and method for modulating optical signal

Abstract: The present invention provides a compact, broad-band, and low-drive-voltage optical modulator module capable of generating any multilevel optical modulation. The optical modulator module according to an exemplary aspect of the present invention includes a digital segmented electrode structure optical modulator and m individual driving circuits. The digital segmented electrode structure optical modulator includes semiconductor optical waveguides and at least m waveguide-type optical phase modulator regions. An i-th individual driving circuit includes a driving circuit and a phase shift circuit. The driving circuit amplifies a digital input signal in synchronization with a clock signal and outputs the signal to an i-th waveguide-type optical phase modulator region. The phase shift circuit applies a delay to a signal branched from the clock signal. A j-th individual driving circuit receives an output signal from the phase shift circuit of a (j−1)-th individual driving circuit as a clock signal.

Light-shift suppression in laser optically pumped vapour-cell atomic frequency standards

Abstract: We present a novel scheme for reducing the AC Stark effect in optical-microwave double-resonance spectroscopy and its application for efficient suppression of the light-shift-related instabilities in laser-pumped gas-cell atomic clocks. The method uses a multi-frequency pump light field that can be easily produced by frequency modulation of the single-frequency pump laser. We show theoretically that variations of the light shift with both laser frequency and light intensity can be strongly suppressed with properly chosen pump light spectra. Suitable modulation parameters can be found for both the case of pure frequency modulation as well as for pump light spectra showing amplitude-modulation contributions, as usually found for current modulation of diode lasers. We experimentally demonstrate the method for a Rb atomic clock using a frequency-modulated distributed Bragg-reflector laser diode as pump light source.